Re: v13: Performance regression related to FORTIFY_SOURCE

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-hackers(at)postgresql(dot)org, Peter Geoghegan <pg(at)bowt(dot)ie>
Subject: Re: v13: Performance regression related to FORTIFY_SOURCE
Date: 2020-06-06 01:39:28
Message-ID: e4e2f350d82dc64bf989146d642a7c15db2595ec.camel@j-davis.com
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On Fri, 2020-06-05 at 14:49 -0700, Andres Freund wrote:
> FWIW, with gcc 10 and glibc 2.30 I don't see such a switch. Taking a
> profile shows me:

...

> 4.65 │ → callq memcpy(at)plt
> │ LogicalTapeWrite():
>
> I.e. normal memcpy is getting called.
>
> That's with -D_FORTIFY_SOURCE=2

That's good news, although people will be using ubuntu 18.04 for a
while.

Just to confirm, would you mind trying the example programs in the GCC
bug report?

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95556

> With which compiler / libc versions did you encounter this?

gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
gcc-9 (Ubuntu 9.2.1-19ubuntu1~18.04.york0) 9.2.1 20191109
libc-dev-bin/bionic,now 2.27-3ubuntu1 amd64 [installed]

Regards,
Jeff Davis

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